Microbiology - Virology-2 Flashcards Preview

Questions

Answers

What must a positive (+) stranded RNA virus do/have to replicate?

Nothing. The positive (+) stranded RNA can immediately be translated by the host’s ribosomes into protein.

3

What must a negative (-) stranded RNA virus do/have to replicate?

Negative (-) stranded RNA viruses must carry, in their capsid, an enzyme called RNA-dependent RNA polymerase.

4

What does the retrovirus carry in order to replicate? How does the retrovirus replicate?

Reverse transcriptase.With reverse transcriptase, RNA is transcribed to DNA. DNA undergoes transcription to mRNA, which is then translated to proteins.

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In a DNA virus, which strand is read?

The positive (+) strand is read, and the negative (-) strand is ignored.

6

What are the two types of capsids?

Icosahedral and helical

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What are the DNA viruses?

Mnemonic: HHAPPPy virusesHerpesHepadnaAdenoPapovaParvoPox

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Which DNA virus is single stranded?

Parvoviridae

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Which DNA virus does not have icosahedral symmetry?

Poxviridae

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Which DNA viruses are naked? Which are enveloped?

Naked: PAPPapovaAdenoParvoEnveloped:HepadnaHerpesPox

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Which RNA virus is double stranded?

Reoviridae

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Which RNA viruses are noneveloped?

Picorna, Calici, and Reoviridae

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Which RNA viruses undergo replication in the nucleus?

Retro and Orthomyxo

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In DNA virus replication, what are the three stages and what is produced during each?

Immediate early and Early: initially transcribed mRNA here encodes enzymes and proteins needed for DNA replication and for further transcription of late mRNA.Late: The capsid structural proteins are synthesized from the late mRNA genome.

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What are the orthomyxoviridae viruses?

Influenza

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What is the structure of the orthomyxoviridae viruses?

The orthomyxoviridae are spherical virions. At the virion cent er lie 8 segments of negative (-) stranded RNA put together with a protein (nucleocapsid protein – NP) into a helical symmetry capsid.

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What are two glycoproteins that stud the outer membrane of the orthomyxoviridae?

What is antigenic drift? Antigenic shift?

Antigenic drift: mutations to the HA or NA, leading to changes in their antigenic nature.Antigenic shift: a complete change of HA, NA, or both.

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What are some differences between Paramyxoviridae and Orthomyxoviridae?

a) the negative (-) stranded RNA is in a single strand, not segmentedb) HA and NA are part of the same glycoprotein spike, not 2 different onesc) Fusion (F) protein causes host cells to fuse together into multinucleated giant cells

21

What are the four paramyxoviridae? Where do they all infect?

What is croup?

Croup is a parainfluenza infection of the larynx and other upper respiratory sructures (laryngotracheobronchitis) that occurs in children. Swelling of these structures produces airway narrowing. Stridor (wheezing sound) and a barking cough occur as air moves through the narrowed upper airways.

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What is the number one cause of pneumonia in young children?

Respiratory Syncytial Virus (especially in infants less than 6 months of age)

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How does RSV differ from the other paramyxoviridae?

RSV lacks both HA and NA glycoproteins

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What structures are involved in mumps virus infection?

Parotid gland (Parotitis)Testes (Orchitis)

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What is another name for Measles? How does it spread?

RubeolaSpreads through nasopharyngeal secretions by air or by direct contact.

What is the path of infection for measles?

What are Koplik’s spots?

A day or two before the rash, patients infected with measles develop small red-based lesions with blue-white centers in the mouth

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What is the measles rash? How does it spread?

The measles rash is red, flat to slightly bumpy (maculopapular).It spreads out from the forehead to the face, neck, and torso, and hits the feet by the third day. As the measles rash spreads downward, the initial rash on the head and shoulders coalesces.

How are the hepatitis viruses transmitted?

What lab values are found in acute viral hepatitis? Why?

AST and ALT are very highGGT, alkaline phosphatase, and bilirubin are slightly elevatedIn viral hepatitis, necrosis of hepatocytes causes the release of AST and ALT. GGT and alkaline phosphate are enzymes found in the bile pericanalicular cells, which are destroyed later on and to a lesser extent. As the infection worsens, the liver swells and the canaliculi narrow, resulting in bilirubin backup.

What causes liver injury during infection with HBV?

Liver injury appears to occur from a cell-mediated immune system attack on HBV. Viral antigens on the surface of infected hepatocytes are targets for cytotoxic T cells. Immune complexes can deposit in tissues and activate the immnune system, resulting in arthritis, and skin and kidney damage.

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What patients are more likely to be asymptomatic carriers of HBV?

Patients who have immunosupressed states, such as malnutrition, AIDS, and chronic illness, are more likely to be asymptomatic carriers because their immune system does not attack.

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What does the presence of HBsAg mean?

The presence of HBsAg always means there is a LIVE virus and infection, either acute, chronic, or carrier.

43

What allows infection of Hepatitis D virus? What are the disease states of HDV and which one is more severe?

HDV is an RNA virus that can only replicate in the presence of HBV envelope, HBsAg.Co-infection: HBV and HDV are transmitted together parenterally.Superinfection: HDV infects a person who has chronic HBV infection. More severe, as lack of Anti-HBsAg allows both viruses to infect chronically.